The present invention relates to swimming pool rescue devices.
Safety swimming pool nets have been represented in the prior art as discussed in the background to this invention. Both hydraulic and mechanical means have been described for raising a net at the bottom of a pool during a potential drowning emergency.
In these cases, the power requirements for performing this task are high since time is of the essence in raising a swimmer in distress to safety. The mechanisms must raise the weight of the potential victim as well as the weight of the net structure and net through resisting water in a short time.
To increase reliability, it is desirable to have redundant power sources and/or an uninterruptable power supply (UPS) to power such a safety system during a power outage. With high power/energy requirements, this is an expensive proposition.
One prior art system uses a submerged inflatable bladder and a storage tank filled with compressed air to quickly inflate the bladder thereby lifting the submerged safety net during an emergency. While fast acting in an emergency, the reliability of rubber-like inflatable bladders over long dormant periods is questionable. The difficulty in deflating such a bladder after use makes it unlikely that safety checks by deployment at scheduled intervals would be actually performed. Also, the requirement of a large diameter hose and an enormous air valve orifice to facilitate rapid inflation have adverse aesthetic and cost consequences.
It is therefore an object of the present invention to provide a reliable device for bringing non-swimmer quickly to the surface of a swimming pool.
In keeping with these objects and others which may become apparent, this invention uses a permanently buoyant safety net structure to avoid many of the shortcomings of the prior art. The only negative aspect of such an approach is the reduction of usable pool depth by three to five inches (76 to 127 mm); this seem to be a small price to pay for the benefits to be described. Mechanisms are used to force the net structure to a ready position at the bottom of the pool and keep it in a ready position for deployment in case of emergency. The buoyant force of the net structure must accommodate lifting a potential victim or victims as well as the net structure itself in a timely manner while encountering water resistance. Thus the potential energy of a submerged buoyant net structure is substantial. This must be provided by the submerging mechanisms after a deployment during a system test or actual emergency. However, this energy can be supplied at a slow rate (i.e.xe2x80x94low power) since this is not an emergency situation.
The latter means that system cost can be reduced as compared to prior art systems since lower power mechanisms with low power wiring or piping requirements are used. Another factor is that there is no reason for a redundant or UPS power supply for this substantial energy requirement since it is not needed during an emergency situation. The very low energy required to trigger deployment of the buoyant submerged safety net can easily be supplied by a small UPS or alternate redundant power supply. This increases system emergency reliability by facilitating the incorporation of such redundant features since the cost for a triggering UPS is low due to its modest energy storage and power requirements.
Finally, the system is fail-safe in the sense that a faulty trigger failing in the false-trigger mode would cause the net to rise in the vicinity of the failed mechanism. This also provides visual cues to a potential problem that can be repaired. The reliability design of actual components must be concerned with jamming of the deployment trigger mechanism and subsystem which is primarily a materials problem to be avoided through accelerated life testing and scheduled routine testing of the entire system by the pool owner. Thus from a system reliability design point of view, the actual design is biased toward false triggering since this is the fail-safe situation.
The safety net of this invention floats about three inches (76 mm) above the surface of the water when floating. In this position, it serves as a protective covering over the entire pool during periods when the pool is not in use or is unattended. By positioning submerging mechanisms where needed along the periphery of the pool, any shape pool can be accommodated even with multiple levels. With the safety net in the floating position, sections can be removed from the attachment to the submerging mechanisms and folded back to permit cleaning, maintenance and repairs of the pool bottom. For security, a wrench with a matching female configuration to special screw heads should be used to prevent unauthorized detachment of the safety net.